The aluminium engineer in Melbourne was a let down but I found a great crew in Sydney who can do exactly what I want for 1/3 Melbourne price. If you are in Oz and looking at this sort of home brew CNC check out Australis Engineering. They are making the whole frame in kit form and shipping it to me ready to assemble, should be here next week.

In the meantime eBay came through with the 3HP water cooled spindle, arrived at the office yesterday.

Pics below, my sparkie is coming over the weekend to test and tag before I power up.

Question:
Anyone have a source for short lengths of VFS motor cable, Belden preferred? All my local wholesalers want me to buy 100 metre rolls.

Herewith the first dry assemble of the frame.
This is only rough to ensure the fabricator sent all the right parts.

Looks OK so far, one minor quibble with the alignment holes at one end but overall very happy with what they did. Cost with freight from Sydney was just over $1k. That may sound high but remember this extrusion goes for over $200 per length and I got them to do all the drilling and tapping plus supply fixings.

Anyhow, off to the hardware store this morning to gather bits for making a proper table, then move onto the full assembly.

To do:

Go 20km across town to the only electrical place that sells the cable I need by the metreTear down an old photocopier at work, fabulous source of limit switches and optical sensors for freeDitto an old 19" rack server, free rack mount case for my electronics and VFDBack to eBay for the linear bearings and railsSource a 600mm ground ball screw for the Z axis, that's my biggest stumbling block so far.

Photos below

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As delivered, lots of tape and shrink wrap. The big parcel weighs about 30kg so still easy to handle

Tapped end with screws. You don't screw through the opposed member, you slide the screw heads into the slots and then use the holes in the other member to get the Allen key in place. It means the system is infinitely adjustable to get everything square.

The access holes

Step One

Finished table frame, this is the bit that slides back and forth on the X axis

Too hot to work in the yard, touching 32 outside so a bit of shed time is needed.
Christmas in Oz, 100 degrees in the shade, shed, beer, CNC, browsing SpudFiles.

I made up the linear slide assemblies for the x-axis last night and this morning, pretty happy with them so far.
Everything is still a dry fit mock up for now, I intend to pretty much assemble the whole thing except for electronics to learn from my mistakes then tear it down and do an accurate final build.

After several hours work, my lady's comment was "so it slides, big deal"

More photos

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Three pillow block bearings mounted to a 1000mm length of profile. Made two of these. Socket head screws make a nice concealed fixing

These are 25mm case hardened rods mounted on an aluminium carrier. Each is 1600mm long.

Like it says, table on rails. The 1600mm rods and the offset bearings allow the 1000mm table to slide completely under the gantry meaning I will get my full cut area.

I am working on the Z-axis design and figure the axis is going to need some compensation for the weight on the ball screw.

The spindle motor and mount come in at 6.4kg, add another 1.5kg for the motor and mounts plus carriage frame etc and I figure I will have 10kg or so suspended on the ball nut.

My figuring says that's close enough to 100 newtons of down force so I am looking at a pair of gas struts mounted either side of the spindle. I don't have a decent drawing of this just now, only a rough sketch but I think I am on the right track.

The question is are gas struts the right way to go given the potential duty cycle of 500 strokes per hour (don't JSR, just leave it alone) or is some type of constant force spring better ? The crude alternative is a counterweight on a pulley but that adds issues with the movement on the Y-axis.

People use all of those successfully. I will likely use gas struts on my mill to lift its 250 lb head when I convert it.

Since were on spudfiles, I would suggest an air spring consisting of air cylinders hooked up to a large air tank. Pump the whole system to the desired pressure, and it will change very little over the stroke of the air cylinder. Just an alternative.

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